Semi-continuous laboratory

Figure 9. Production of T. viride cellulose in a semi-continuous laboratory fermenter...

However, in actual test measurements, at what point, if any, can it be said that all the feed passes through the membrane That is to say, does not holdup occur on the upstream pressure side For in any kind of short-term or transient test (say, in what might be called a batch or semi-continuous laboratory or bench-scale test), does a reject phase not exist at any point At any point in time, is there no situation in which the feed that has not yet passed through the membrane constitute a reject phase Only for a long-term, steady-state test—with no reject sidestream—can it truly be said that all the feed passes through the membrane. This sort of long-term test, properly speaking, then provides the true measure of membrane permeability for the components within a mixture. Whether or... 

The effects of treatment at 15-50°C on some of the characteristics were studied by Evans et al (4) using laboratory reactors. These were fed semi-continuously, with feed intervals of 5-20 min, and DO was maintained at about 20% of saturation. The treatment conditions were thus similar to the high DO treatments used in the present study, but the main difference was that Evans etal s 3 and 15 litre reactors were smaller than those used in the present study by factors of 167 and 33 respectively. Evans etal s expression for TS and COD take the form ... 

Laboratory studies of the rearrangement process began with semi-continuous operation in a single, 200-mL, glass reactor, feeding 1 as a liquid and simultaneous distillation of 2,5-DHF, crotonaldehyde and unreacted 1. Catalyst recovery was performed as needed in a separatory funnel with n-octane as the extraction solvent. Further laboratory development was performed with one or more 1000-mL continuous reactors in series and catalyst recovery used a laboratory-scale, reciprocating-plate, counter-current, continuous extractor (Karr extractor). Final scale-up was to a semiworks plant (capacity ca. 4500 kg/day) using three, stainless steel, continuous stirred tank reactors (CSTR). 

However, it can be assumed for most electrochemical applications of ionic liquids, especially for electroplating, that suitable regeneration procedures can be found. This is first, because transfer of several regeneration options that have been established for aqueous solutions should be possible, allowing regeneration and reuse of ionic liquid based electrolytes. Secondly, for purification of fiesh ionic liquids on the laboratory scale a number of methods, such as distillation, recrystallization, extraction, membrane filtration, batch adsorption and semi-continuous adsorption in a chromatography column, have already been tested. The recovery of ionic liquids from rinse or washing water, e.g. by nanofiltration, can also be an important issue. 

This study focuses firstly on the transfer of regeneration principles as they have been developed in the field of water-based electroplating and of purification options for ionic liquids as they are experienced in other fields of ionic liquid application. A number of purification procedures for fresh ionic liquids have already been tested on the laboratory scale with respect to their finishing in downstream processing. These include distillation, recrystallization, extraction, membrane filtration, batch adsorption and semi-continuous chromatography. But little is known yet about efficiency on the technical scale. Another important aspect discussed is the recovery of ionic liquids from rinse or washing water. 

A comparison of data from a laboratory evaluation by O Rourke (5) of methane fermentation at 35 °C and using sludge from a primary municipal waste treatment plant is illustrated in Figure 6. The digesters were operated on a semi-continuous basis, receiving waste at least once per day and more frequently than this at the lower 6c of 2.5 days. The results are quite comparable with those obtained from the continuous feed... 

Attempts to increase pyrite removal by increasing the reaction time met with limited success under our standard conditions because reaction of the ferric ion with the coal matrix depleted the ferric ion that was needed for extraction of the pyrite. Thus, for example, increasing the coal reaction time from 2 to 12 hrs only increased pyritic sulfur removal from 60 to 80% for Pittsburgh coal. Similar results were obtained for the other three coals. The only alternatives were to increase the amount of leach solution or to use a continuous or semi-continuous (multiple-batch) reactor. A multiple-batch mode was chosen because it was a simple laboratory procedure and at the same time it could approximate conditions encountered in a commercial plant. A 1-hr-per-batch leach time was used because our 2 hr results indicated that in the early stages of removal the rate begins to decrease after 1 hr, and six leaches (or batches) per run were used to assure that any pyrite that could be removed in a reasonable amount of time was removed. The progress of removal was monitored by analyzing the sulfate content in each spent leach solution elemental sulfur was not removed until all the leaches were completed. Table VII shows pyrite extraction as a function of successive leaches as followed by sulfate analysis of the leach solution. Note that the major portion of pyritic sulfur is removed in the first two leaches or 2 hrs, followed by lesser amounts in... 

We are currently constructing a laboratory scale semi-continuous unit which will use the prehydrolysis concept. 

The indoor facility comprises a 20 x20 x40 thermally insulated enclosure that is continually flushed with purified air at a rate of 1000 L min and is located on the second floor of a laboratory building specifically designed to house it. Located directly under the enclosure on the first floor is an array of gas-phase continuous and semi-continuous gas-phase monitors. Within the enclosure are two 90 m (6.1 m x 3.1 m x 5.5 m, Siuface area to volume = 1.35 m ) 2 mil FEP Teflon film reactors, a 200 kW Argon arc lamp, a bank of 72 W 4-ft blacklights, along with the light and aerosol instrumentation. A schematic of the enclosure is provided in Figure 1. 

Cartridge and membrane filter systems tested in preliminary studies in our laboratories have proved to be applicable to eukaryotic cell culture processes, i.e. cell removal, semi-continuous culture growth, cell culture concentration and recycling. Present membrane systems are limited in processing volume cartridges are scalable, but have a narrower range of application. 

While we have not investigated fermentation technology in detail, we have used a laboratory fermenter to produce large quantities of T. viride cellulase in a semi-continuous system. The effluent from the fermenter has been used by Ghose in his digestion experiments (7) with no treatment other than filtration through glass wool and pH adjustment. 

Although simple and rectified batch distUlation are the methods most used in the laboratory, they are not the only ones. Procedures employed mainly in industry have also been added to the laboratory repertoire. In order to increase output, semi-continuous and continuous processes have been adopted, whilst in certain cases partial condensation also presents advantages. 

Before considering the two classes of batchwise process in detail, it is important to have a clear understanding of the simple distinction between them. In batch processes all reactants are completely added to the reaction vessel at the start of the polymerization, whereas in semi-batch processes (also referred to as semi-continuous batch processes) only part of the total reaction formulation is introduced at the beginning of the reaction, the remainder being added, according to a predetermined schedule, during the course of the polymerization. Batch processes are of limited versatility for manufacture of latexes and mainly find use in academic studies and simple evaluations of reaction formulations. By comparison, semi-batch processes are very versatile and are widely used, both industrially and in academic laboratories. 

The realization of the comparison between macroscale semi-continuous batch and a continuous microscale process on the laboratory scale was carried out for several reasons. First, it was of marked interest whether ecological improvements can be expected for the chosen model reaction performed in microstructured devices. Such improvements were the premise for the transfer of this model reaction to the... 

Batch polymerisations are often performed in screening experiments on the laboratory-scale level. However, batch polymerisations are used less often in large-scale, commercial produchon processes than semi-continuous polymerisations because of the inherent limitations in heat transfer and copolymer composition control. 

An exceptionally simple method for separating many metathesis products from the catalyst is to extract the former into supercritical carbon dioxide [30]. Presumably, this is only effective in examples of relatively nonpolar products, which of course many are. The procedure can be run as a semi-continuous process, although the availability of suitable equipment will likely be a problem in many laboratories. 

Delannay E, Toribio A, Boudesocque L, Nuzillard JM, Zeches-Hanrot M, Dardennes E, Le Dour G, Sapi J, Renault JH (2006) Multiple dual-mode centrifugal partition chromatography, a semi-continuous development mode for routine laboratory-scale purifications. J Chromatogr A 1127 45-51... 

Standard fed-batch operation is not economically viable due to solvent toxicity, so the system can be coupled with an in situ recovery process (Lee et al. 2008 Ezeji et al. 2004a, b). Fed-batch fermentation is used principally in laboratories, but it cannot be applied without in situ product removal due to its strong cell inhibition. Semi-continuous operation is also used in industrial practice in order to avoid strain degeneracy (Branduardi et al. 2014 Xue et al. 2013a). 

In continuous and semi continuous-flow systems waste go into reactor continuously or at certain intervals. The introduction of a new portion of feedstock is accompanied by a simultaneous discharge of an equivalent quantity of the batch of reactor. Part of the material leaves the reactor without being completely decomposed. Parameters determined in these systems are called biogas/methane yield. Some results of laboratory estimation of biogas production from waste are presented in Table 2.5. 

Putrescible fraction of food market waste Laboratory scale semi-continuous reactor, V = 3 dm mesophilic conditions (35 Q HRT 8-20 OLR <3 kg VS m- d- 0.478m CH,kgVS.,- Mata-AIvarez etal. (1992)... 

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